The present invention is directed to a recording device functioning with fluid droplets for point-by-point recording of analog progressions and/or alphanumerical characters as well as images. The device includes a plurality of nozzles, which have inlet openings and outlet openings and which are arranged in a row with a recording medium being disposed in front of the discharge openings of the nozzles to enable writing individual points on the medium. A piezoelectric transducer is provided in front of the intake openings of the nozzles and each of the transducers are provided with means for applying an electrical voltage so that with a given electrical voltage change the writing fluid is ejected from the particular nozzle. The individual transducers are formed by teeth of a comb-like piezoelectric plate which plate is a bilaminar plate of a piezoelectric ceramic layer and a carrier layer.
A recording device, wherein the plate material consists of a layer of piezoceramic material and a metal layer is disclosed in U.S. Pat. No. 4,072,959, which was based on German No. OS 2,527,647 and whose disclosure is incorporated by reference thereto. In this patent, a piezoplate comprising a layer of piezoceramic material and a carrier layer is disclosed which plate has a comb-like structure with parallelly extending teeth forming the individual transducers. In one embodiment, a spacer piece is provided between a nozzle plate and the comb-like piezoelectric plate. The comb is held in position by means of a clamp that extends over the entire length of the spine of the comb. The problem with this design is that the clamping of the comb in the clamp must occur with extreme precision. Since the thickness of the comb only amounts to a few tenths of a millimeter, a displacement between the spacer piece and the clamp of the same order of magnitude will lead to considerable changes in the flexural forces. The flexural lengths of the transducers in the two twist directions become different as a consequence and this will lead to imprecise writing.
Given the traditional comb fixing, it must also be taken into consideration that the clamp comes into contact with all of the transducers of the comb precisely and with identical force insofar as possible. This is required so that the flexural length of all the transducers will remain identical. This is particularly difficult to achieve in the case of the central transducers of the comb which therefore tend to bend below the clamp.